KR20020024547A - Method for fabricating a laminate film, laminate film, and method for fabricating a display device - Google Patents

Abstract

PURPOSE: A method for fabricating a laminate film, a laminate film, and a method for fabricating a display device are provided to improve the viewing angle characteristics by using a laminate film. CONSTITUTION: Adhesive layers(52,54) are formed on the two opposing surfaces of a transparent support(53). At least one of the adhesive layers is made of a material of which the cured state changes by application of external force, such as a photocurable resin. A separator(51a) on the adhesive layer is peeled off, and the adhehesive layer is irradiated with light. A lens sheet is pressed against the adhesive layer. The adhesive layer is cured to a degree of hardness with which the adhesion state between lens sheet and the adhesive layer no more changes. Consequently, a laminate film of the lens sheet fixed to the transparent support via the adhesive layer is obtained. The laminate film is bonded to a polarizing plate on the viewer's side of a liquid crystal display element via the other adhesive layer.

Description

Laminated film manufacturing method, laminated film, and display device manufacturing method {METHOD FOR FABRICATING A LAMINATE FILM, LAMINATE FILM, AND METHOD FOR FABRICATING A DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a laminate film, and more particularly, to a method of manufacturing a display device (for example, a liquid crystal display) having improved viewing angle characteristics using a laminate film.

Liquid crystal displays representing flat panel displays are lighter, thinner, and have lower power consumption than CRTs, so that they are wider, such as OA devices, car TV sets, car navigation systems, and video camera monitors. Applied in a wide range of fields.

The main problem associated with such a liquid crystal display is that it is highly visually dependent. Visual dependence refers to the following phenomenon, for example. When the screen of the display device is observed from an inclined direction by an angle exceeding a certain angular range, an image which should be displayed correctly in black appears slightly white, or the gray scale level is inverted, thereby reducing the quality of the display. . From this viewing direction, the observer does not correctly recognize the display image. It is said that the visual dependence is large when the angular range in which the observer correctly recognizes the displayed image is narrow.

There are many reasons for visual dependence. For example, the twisting direction of the liquid crystal molecules (i.e., the spiral structure) (the spiral direction, the position at which the liquid crystal molecules start to form a spiral defined by the friction direction), the refractive index anisotropy of the liquid crystal molecules (the difference in the amount of retardation in the traveling direction of light ), The characteristics of the polarizing plate (whether the selectivity of the light vibration direction is good), and the directivity of the light beam from the surface light source.

In general, transmissive liquid crystal display devices are designed such that, in view of the visual dependence described above, the display is best positioned within the range in which the observer generally observes the display. For example, the design may be designed to enhance the contrast ratio of the center of the screen compared to the screen periphery in the normal direction of the screen or slightly downward from the viewer.

However, the visual range is not yet sufficient with the above structure. In particular, the liquid crystal display has large visual dependence in the vertical direction with respect to the screen. In order to solve this problem, various methods have been conventionally proposed.

For example, Japanese Laid-Open Patent Publication No. 7-43703 discloses a liquid crystal display device in which a material is filled between a microlens array sheet and a liquid crystal display element. The material has a refractive index equal to or less than the refractive index of any of the materials constituting the microlens array sheet and the liquid crystal display element.

Japanese Unexamined Patent Publication No. 10-73808 discloses a liquid crystal display device in which a light diffusion sheet is placed on a front surface of a liquid crystal display element. The light diffusion sheet includes a first diffusion layer containing a light diffusing agent formed on the transparent body, and a second diffusion layer having uneven portions formed on the first diffusion layer.

In all of the above conventional techniques, the microlens array sheet is disposed on the polarizing plate constituting the liquid crystal display element. A material having a refractive index different from that of the microlens array sheet is provided between the microlens array sheet and the polarizing plate.

Japanese Unexamined Patent Publication No. 7-120743 discloses a liquid crystal display device in which the convex top portion of the microlens array sheet is in close contact with the surface of the liquid crystal display element.

Japanese Unexamined Patent Publication No. 9-127309 disclose a liquid crystal display device in which an adhesive layer is formed on a top of a convex portion of a microlens sheet. The ratio (A / B) of the height A of the convex portion to the thickness B of the adhesive layer should be greater than 1 and less than or equal to 1000.

Japanese Unexamined Patent Publication No. 9-194799 discloses a liquid crystal display in which a spacer is disposed between the rough surface and the adhesive layer.

In the above conventional technique, the convex top portion of the microlens array sheet is partially disposed in contact with the liquid crystal display element through the adhesive layer, thereby controlling the ratio of the lens array contact portion to the non-contact portion. In this way, the degree of transmission and divergence of the emitted light is controlled to improve the visual characteristics. In any case, since the microlens array sheet is disposed on the liquid crystal display element side closer to the observer (observer side), the outgoing light from the liquid crystal display element diffuses to the side where the microlens is formed (lens formation direction), thereby improving visual characteristics. do.

The prior art has the following problems.

In general, a pair of polarizing plates are disposed on the front and rear surfaces of the liquid crystal display device to control the polarization state before displaying an image.

The polarizer is composed of polyvinyl alcohol (PVA) and triacetyl cellulose (TAC). Iodine penetrates into the PVA, and the resulting material is drawn in one direction to align the iodine molecules, so that polarization is absorbed (or transmitted) along the pulled direction so that the polarization state of the incident light can be uniformly aligned. have.

During the stretching, as shown in FIGS. 22A and 22B, minute waves 222 are generated on the surface of the polarizing plate 221 along the absorption axis (or transmission axis) in the stretching direction. This is due to the small thickness change of the polarizing plate 221 generated by stretching. These waves do not affect the display device when observed only through the polarizer 221. However, as shown in FIG. 23B, when the light emitting element 235 such as the microlens array sheet is disposed on the surface of the polarizing plate 231, in particular, the light emitting element 235 is disposed through the adhesive layer 234. When coupled to 231, the wave 232 generated on the surface of the polarizer is magnified. As a result, display quality deteriorates much.

Display quality is also greatly degraded when the conventional double-sided adhesive tape is used as the adhesive layer 234 to bond with the light diffusing element 235 and when the curable resin is used as the adhesive layer 234. In these cases, the contact area between the light diffusing element 235 and the adhesive layer 234 is formed by the impact of foreign matter generated in the bonding process (deformation of irregularities caused by foreign matter) and deformation caused by external force (lens surface By some observer touching it. Some of these changes in contact area result in spot defects 233a and rod defects 233b, as shown in FIG. 23A.

The prior art does not mention any means for solving the above problem.

SUMMARY OF THE INVENTION An object of the present invention is a laminated film that allows an optical film to be uniformly bonded to a surface (for example, the surface of a display element) even if the surface is uneven, a method of manufacturing such a laminated film, a display device using such a laminated film, and such It is to provide a method of manufacturing a display device.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic explanatory drawing of the liquid crystal display device in Example 1 of this invention.

2A and 2B illustrate an example array of R, G, and B pixels.

3A and 3B illustrate a lens sheet in Embodiment 1 of the present invention.

4 is a view for explaining a surface light source in Embodiment 1 of the present invention.

5A, 5B, 5C, and 5D are views for explaining a manufacturing process for the liquid crystal display device according to the first embodiment of the present invention.

6A, 6B, 6C, and 6D are views for explaining a manufacturing process for the liquid crystal display device in Example 1 of the present invention.

7A and 7B are views explaining manufacturing steps for the liquid crystal display device in Example 1 of the present invention.

8A and 8B are views for explaining a modification of the manufacturing process for the liquid crystal display in Example 1 of the present invention.

9 is a view for explaining a roller moving direction in a step of pressing a lens sheet with respect to an adhesive layer.

The figure explaining the roller movement direction in the process of crimping a lens sheet with respect to an adhesive layer.

11 is a schematic explanatory diagram of a bonding state between an adhesive layer and a lens convex portion of a lens sheet.

Fig. 12 is a diagram showing luminance characteristics of the liquid crystal display device according to the first embodiment of the present invention.

Fig. 13 is a diagram showing the viewing angle characteristics of the liquid crystal display device according to the first embodiment of the present invention.

Fig. 14 is a schematic explanatory diagram of a liquid crystal display device in Example 2 of the present invention.

15 is a diagram illustrating a display principle of a reflective liquid crystal display device.

16A and 16B illustrate a prism sheet in Embodiment 2 of the present invention.

17A, 17B, 17C, and 17D are views for explaining a manufacturing process for the liquid crystal display device in Example 2 of the present invention.

18A, 18B, 18C, and 18D are views for explaining a manufacturing process for the liquid crystal display device in Example 2 of the present invention.

19A and 19B illustrate manufacturing steps for the liquid crystal display device according to the second embodiment of the present invention.

20A and 20B are diagrams illustrating a modification of the manufacturing process for the liquid crystal display device according to the second embodiment of the present invention.

Fig. 21 is a diagram explaining an offset of the optical axis in the liquid crystal display in the second embodiment of the present invention.

22A and 22B illustrate waves on a polarizing plate.

23A and 23B are diagrams illustrating deterioration in display quality due to waves on a polarizing plate.

<Explanation of symbols for main parts of the drawings>

10: liquid crystal display

11: surface light source

12a, 12b, 57a, 57b, 144a: polarizer

13a, 13b, 58a, 58b, 141a, 141b: substrate

15, 55: lens sheet

16a, 16b, 52, 54, 145a, 145c: adhesive layer

16c, 145b: transparent support

51a, 51b: separator

56: adhesive film

140: reflective liquid crystal display device

142: reflector

146: prism sheet

According to a first aspect of the present invention, there is provided a method of producing a laminate film comprising a transparent support having two opposing surfaces and an optical film. The optical film is formed on one of two opposing surfaces of the transparent support via an adhesive layer formed of a material whose curing state is changed by applying external energy. The method includes applying external energy to the adhesive layer; Pressing the optical film against the adhesive layer to bond the optical film and the adhesive layer; And curing the adhesive layer to a hardness at which the adhesive state between the adhesive layer and the optical film is fixed while the optical film and the adhesive layer are bonded to each other.

In one embodiment of the present invention, the adhesive layer is formed of an ultraviolet-curing resin.

Preferably, the step of curing the adhesive layer includes the step of leaving the adhesive layer and the optical film in a state in which the adhesive layer and the optical film are bonded. More preferably, curing the adhesive layer includes leaving the adhesive layer and the optical film in a state in which the adhesive layer and the optical film maintain the bonding so that the gel fraction of the adhesive layer is 50 wt% or more.

On the adhesive layer, a surface protective film may be provided to protect the adhesive layer, and the thickness t of the surface protective film is in the range of 0.035 mm ≤ t ≤ 0.2 mm, and the method also removes the surface protective film before the step of pressing the optical film against the adhesive layer. It may include the step.

The other of the opposing surfaces of the transparent support may be joined to the rough surface via an adhesive layer. Preferably, the rough surface is the surface of the film made by stretching. The rough surface may comprise an area having a flatness Rt1 that satisfies Rt1 > 2 μm when the distance between the highest and deepest within the range of lengths to be evaluated as the roughness Rt1.

Preferably, the transparent support has a flatness Rt2 that satisfies Rt2 ≦ 2 μm when the distance between the highest and deepest points in the range of lengths to be evaluated as the flatness Rt2.

The optical film may be a lens sheet having a plurality of lenses formed on at least one surface, and the surface having the plurality of lenses may be pressed against the adhesive layer opposite the adhesive layer. Preferably, the lens sheet is a lenticular sheet having a plurality of semi-cylindrical lenticulars arranged parallel to each other, wherein the lenticular sheet has a surface having a plurality of lenticulars facing the adhesive layer, so that the lenticular expansion It is pressed against the adhesive layer by the force applied in the direction. Alternatively, the optical film may be a prism sheet having a plurality of prisms.

According to the second aspect of the present invention, a laminated film is provided. The laminated film includes: a transparent support having two opposing surfaces; An adhesive layer formed on one of two opposing surfaces of the transparent support; And an optical film coupled to the transparent support through the adhesive layer. In that film, the adhesive layer is composed of a material whose curing state is changed by the application of external energy, and the transparent support is defined as the flatness Rt as the distance between the highest and the deepest within the range of the evaluated length, Rt ≤ It has a flatness Rt that satisfies 2 μm.

Preferably, the adhesive layer has a gel fraction of at least 50 wt%.

The optical layer may be a lens sheet having a plurality of lenses formed on at least one surface, and the surface having the plurality of lenses may be pressed against the adhesive layer opposite the adhesive layer. The optical film may be a prism sheet having a plurality of prisms.

According to a third aspect of the present invention, there is provided a method of manufacturing a display device including a display element and an optical film disposed on the observer side of the display element. The method comprises: making a display element; And bonding the optical film to the surface of the display element at the observer's side through the adhesive film, wherein the adhesive film comprises a transparent support having a first contact layer formed on one of two opposing surfaces, the first contact layer Is composed of a material whose curing state is changed by the application of external energy, and the bonding of the optical film to the surface of the display element on the observer side comprises: applying external energy to the first adhesive layer; Pressing the optical film against the first adhesive layer to bond the optical film and the first adhesive layer; Curing the first adhesive layer to a hardness at which the adhesion state between the optical film and the first adhesive layer is fixed while the optical film and the first adhesive layer maintain bonding; And after curing of the first adhesive layer, bonding the display element with the other one of the two opposite surfaces of the transparent support via the second adhesive layer.

In a preferred embodiment of the present invention, the display element has an optical characteristic that changes the optical characteristics of a pair of substrates, a liquid crystal material positioned sandwiched between the pair of substrates, and incident light disposed on at least the observer side of the pair of substrates. A liquid crystal display device including a changing means, wherein the optical film is bonded to the liquid crystal display device by bonding the optical property changing means and the transparent support of the adhesive film through the second adhesive layer.

The first adhesive layer is composed of an ultraviolet-curable resin.

Curing the first adhesive layer may include leaving the first adhesive layer and the optical film in a state in which the first adhesive layer and the optical film maintain the bonding.

Curing the first adhesive layer may include leaving the first adhesive layer and the optical film in a state in which the first adhesive layer and the optical film maintain the bonding so that the gel fraction of the first adhesive layer is 50 wt% or more.

Preferably, a surface protective film is provided on at least the first adhesive layer to protect the first adhesive layer, the thickness t of the surface protective film is in the range of 0.035 mm ≦ t ≦ 0.2 mm, and the method further comprises pressing the optical film against the first adhesive layer. It may include the step of peeling the surface protective film before the step.

Preferably, the surface of the display element combined with the second adhesive layer has an area having a flatness Rt1 that satisfies Rt1 > 2 μm when the distance between the highest and the deepest points within the range of the evaluated length is defined as the flatness Rt1. Include.

Preferably, the transparent support has a flatness Rt2 that satisfies Rt2 ≦ 2 μm when the distance between the highest and deepest points in the range of lengths to be evaluated as the flatness Rt2.

The means for changing the optical properties may be a polarizing plate. Alternatively, the optical property changing means may be a phase plate.

The optical film may be a lens sheet having a plurality of lenses, and a surface having a plurality of lenses may be pressed against the first adhesive layer, facing the first adhesive layer.

Preferably, the lens sheet is a lenticular sheet having a plurality of semi-cylindrical lenticulars arranged in parallel to each other, the lenticular sheet is a force applied to the direction of expansion of the lenticular, the surface having a plurality of lenticular opposing the first adhesive layer Is pressed against the first adhesive layer. Alternatively, the optical film can be a prism sheet having a plurality of prisms.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a display device including a display element and a lens sheet disposed on an observer side of the display element. The lens sheet has a plurality of lenticulars arranged parallel to each other. The method comprises: making a display element; Forming an adhesive layer on an observer side of the display element; Disposing the lens sheet such that the lens surface of the lenticulars faces the adhesive layer; And pressing the lens sheet against the adhesive layer by applying a force in the direction of extension of the lenticulars.

Hereinafter, the function of the present invention will be described.

In the method for producing a laminated film according to the present invention, after external energy is applied to an adhesive layer made of a material whose curing state is changed by the application of external energy, the optical film (for example, the lens sheet) is pressed against the adhesive layer. This process step is carried out while the material is in the B stage (intermediate curing state). Subsequently, the adhesive layer is cured to a hardness at which the adhesion state between the optical film and the adhesive layer is no longer changed, thereby completing the laminated film. After this curing step, the material of the adhesive layer is at or near the C stage (completely cured state). In this laminated film, the adhesion state of the optical film is fixed by the transparent support through the adhesive layer. Therefore, when the laminated film is bonded to the rough surface, the shape of the rough surface is transferred to the optical film and prevented from affecting the optical properties of the optical film. The effect of the present invention is particularly great when the optical film has an uneven portion formed on its surface in contact with the adhesive layer, and the area of the contact area between the convex portion and the adhesive layer affects the optical properties of the optical film.

In particular, when the adhesive layer for bonding the optical film and the transparent support is composed of a photocurable resin, the optical film and the transparent support can be easily combined and fixed together. This reduces the occurrence of defects due to external forces or failures.

By arranging the surface protective film on the outer surface of the adhesive layer in the adhesive film and setting the thickness t of the surface protective film in the range of 0.035 mm ≤ t ≤ 0.2 mm, the adhesive layer is prevented from being deformed due to the presence of external materials and external forces before curing. . As a result, the coupling between the light emitting element and the transparent body becomes easy.

The method of manufacturing the display device according to the present invention also has the function described above in connection with the method of manufacturing the laminated film. In particular, when using a liquid crystal display element as a display element, a wave tends to generate | occur | produce on the surface of the polarizing plate and retardation plate of a display element. When the optical film is coupled to the polarizing plate or the retardation plate in an attempt to improve the characteristics of the display element, waves of the polarizing plate or the retardation plate are transmitted to the optical film. However, according to the manufacturing method of the present invention, after the adhesive layer is cured such that the adhesion state between the optical film and the adhesive layer is no longer changed, the laminated film is bonded to the display element. Therefore, it is possible to prevent the non-uniform surface of the display element from affecting the optical film, thereby preventing deterioration of display quality. In particular, when the lens sheet is bonded to the liquid crystal display element by the manufacturing method according to the present invention with an optical film, the resulting liquid crystal display device can exhibit high display quality with improvement of visual characteristics.

By arranging the surface protective film on the outer surface of the adhesive layer formed on the transparent support and setting the thickness t of the surface protective film in the range of 0.035 mm ≤ t ≤ 0.2 mm, the adhesive layer is deformed due to the presence of external material or external force before curing. prevent. As a result, the coupling between the optical film and the transparent support becomes easy. In particular, spot defects and rod defects affect the optical performance of the light emitting device. A defect having a diameter of 0.1 mm or more is observed as a panel defect, which significantly reduces the display quality.

By controlling the thickness of the surface protective film, the number of point defects and rod-shaped defects can be greatly reduced. For example, if the number of defects is 200 pieces / m ² when the thickness of the surface protective film is 0.02 mm, it may be reduced to 50 pieces / m ² when the thickness is 0.035 mm. For example, in a 20-inch liquid crystal display, 25 defects may be reduced to 10 or less. Therefore, the display quality is improved.

Although thicker surface protective films can reduce the number of defects, the cost of the material is high, which increases the cost. Therefore, the thickness is preferably 0.2 mm or less.

The present inventors have suffered from the problems of the prior art described above, that is, the display quality deteriorates greatly when a light emitting element such as a microlens array sheet is disposed on the surface of a polarizing plate. It was first discovered that the wave on the polarizing plate affects the adhesion state between the uneven surface of the sheet and the adhesive layer. The present invention has been made based on this finding.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(Example 1)

1 is a cross-sectional view of a liquid crystal display device used in Example 1 of the present invention. Referring to FIG. 1, the liquid crystal display device of this embodiment includes a surface light source 11, a liquid crystal display element 10, and an adhesive layer 16 and a lens sheet (lens film) 15 as an optical film. A laminate film 17 is provided.

The liquid crystal display device 10 basically includes: an active matrix including a thin film transistor (TFT), a transparent pixel electrode, and the like, formed in a matrix on a transparent substrate formed of glass or plastic. ) Substrate 13a; A counter substrate 13b including a transparent electrode and a color filter formed on a transparent substrate formed of glass or plastic; A liquid crystal material 14, which is a display medium sealed in a space between two substrates; And a pair of polarizing plates (polarizing films) 12a and 12b arranged to be sandwiched between the two substrates.

In this embodiment, a twisted nematic (TN) liquid crystal material having a twist angle of 90 degrees is used as the liquid crystal material 14. As the liquid crystal display device 10, various kinds of pixels having different numbers and sizes may be used. In this embodiment, the screen size is 20 inches (304.8 mm x 406.4 mm) diagonally, and a stripe array of R, G, and B pixels shown in FIG. 2A has a horizontal pixel count of 640 (R, G, B). Respectively) x liquid crystal display element having 480 vertical pixels, a horizontal pixel pitch Ph of 0.212 mm, and a vertical pixel pitch Pv of 0.635 mm.

The color filter does not necessarily need to be provided to the counter substrate 13b. For example, it may be formed in the pixel electrode of the active matrix substrate 13a.

The outer surface of the polarizing plate 12b located on the observer side of the liquid crystal display element 10 includes an adhesive layer (first adhesive layer) 16a, a transparent support 16b, and another adhesive layer (second adhesive layer) 16c. The lens sheet 15 is disposed through the adhesive film 16.

In the present embodiment, as the lens sheet 15, a lenticular sheet having a plurality of semi-cylindrical lenticules arranged in rows is used. Note that the lens sheet indicated by reference numeral 30 in FIG. 3 is the same as the lens sheet 15 of FIG. 1. The lenticular sheet 30 is positioned so that the lenticular extends in parallel with the horizontal (horizontal) direction on the screen of the liquid crystal display device.

In this embodiment, the lenticular sheet 30 was manufactured by the following method. First, the ultraviolet-curable resin (Z9001, refractive index n = 1.59) manufactured by JSR was dropped in the metal mold | die which is the shape of a recessed part repeatedly. The ultraviolet-curable resin was then irradiated with ultraviolet light of 1.0 J / cm ² , thereby repeatedly carrying convex portions on the base plate 33 to form it. As the base plate 33, an ARTON membrane manufactured by Japan Synthetic Rubber was used. In this way, a lenticular sheet having a pitch P1 of 0.05 mm and a height h of 0.015 mm was produced.

A light-shading layer 32 was formed on the entire surface of the lenticular 31 to prevent surface reflection of the lenticular sheet 30. More specifically, the light shielding sheet 32 was formed by the following method. The lenticulars 31 was coated with an organic material in which black dye was dispersed by a printing method. Subsequently, 1.5 J / cm <^2> ultraviolet light was irradiated and hardened | cured to the organic material. The thickness of the light shielding layer 32 was controlled to about 0.005 mm so that the total light transmittance of the lenticular sheet 30 was 70%.

Although the luminance of the liquid crystal display increases as the total light transmittance increases, the decrease in luminance of the liquid crystal display is negligibly small as long as the total light transmittance is 50% or more.

4 illustrates a surface light source used in this embodiment. In FIG. 4, the surface light source 11 of FIG. 1 is indicated by the reference numeral 40.

The surface light source 40 used in the present embodiment is a side emitting type, and basically reflectors 42a and 42b surrounding the cold cathode tubes 41a and 41b, the cold cathode tubes 41a and 41b, the diffuse reflection sheet 47, It consists of the optical conductor 43 in which the silk printing 44 was formed, the diffusion sheet 45 arrange | positioned at the exit side of light, and the DBEF film 46 (made by 3M company). Since the surface light source 40 having the above structure can be manufactured by a known method, description thereof is omitted here.

Next, the laminated film used in the present embodiment will be described.

The lens sheet 15 is coupled to the polarizing plate 12b of the liquid crystal display element on the observer side, as shown in FIG. In this case, when an adhesive layer such as a double-sided adhesive tape is first formed on the polarizing plate 12b, and then the lens sheet 15 is bonded to the adhesive layer, irregularities on the surface of the polarizing plate 12b, in particular, waves on the surface of the optical film The influence of the uneven portion is reflected on the surface of the lens sheet 15 to change the optical properties.

In particular, in the present embodiment, the lens sheet is disposed such that the uneven portion faces the adhesive layer and the lens tip is embedded in the adhesive layer. Since the normal adhesive layer has a refractive index similar to that of the lens sheet material, the lens tip embedded in the adhesive layer no longer satisfactorily functions as a lens. In other words, the contact area between the lens layer and the adhesive layer between the air layer and the lens sheet operates to generate the refraction required for the lens effect. Therefore, the size and in-plane uniformity in the contact region between the lens tip and the adhesive layer have a great influence on the lens properties.

In view of the above, if the contact area between the lens tip and the adhesive layer is relatively large in some areas of the lens sheet, while in other parts of the lens sheet, the optical properties (lens properties) of the lens sheet are distorted within the screen. do.

If the uneven surface of the optical sheet is directly bonded to the uneven surface of the back layer such as the polarizing plate through the adhesive layer as described above, the surface uneven portion (wave) of the polarizing plate is the contact area between the lens tip of the lens sheet and the adhesive layer. Is changed in the sheet surface. As a result, the lens characteristics of the lens sheet are distorted to reflect the irregularities and waves of the back layer.

In order to prevent the above problem, in this embodiment, the transparent support 16b and the lens sheet 15 having a predetermined planarity are pressed together through the adhesive layer 16a. Subsequently, the adhesive layer 16a is cured to a predetermined hardness, that is, to a hardness at which the adhesive state between the optical film and the adhesive layer no longer changes. Thereafter, the resulting laminated film of the lens sheet 15 and the transparent support 16 joined together is bonded to the polarizing plate through the adhesive layer 16c. Thus, the contact state between the lens sheet 15 and the adhesive layer 16a can be kept constant by the transparent support 16b having a predetermined planarity. Therefore, when the laminated film including the lens sheet 15 is bonded to the polarizing plate in a subsequent process, the contact state between the lens sheet 15 and the adhesive layer 16a is affected by irregularities such as waves on the surface of the polarizing plate. It is prevented from receiving, and the characteristic of an optical film is not distorted.

The planarity of the transparent support is described.

Table 1 below shows the results of the inventor's investigation on the influence of the surface planarity (roughness) of the backing film on the optical film when the optical film is bonded to the backing film.

Flatness Rt on the back Rear effect Rt> 2 μm X impossibility 2μm ≥ Rt ≥ 1.5μm △ 1.5 μm> Rt> 1 μm O good 1μm ≥ Rt ◎ excellent

Planarity (flatness) Rt is defined as the distance between the highest and deepest within the range of lengths evaluated. As can be seen from Table 1, when the flatness Rt of the back film is 2 μm or less, the influence of the surface shape of the back film on the optical properties of the optical film is acceptable. Therefore, in the manufacturing method of the present invention, the transparent support is formed of a material having a flatness Rt of 2 m or less. In addition, as can be seen from Table 1, the flatness Rt is preferably smaller than 1.5 μm, more preferably 1 μm or less.

Conversely, a film prepared by stretching a material in one direction, such as a polarizing plate and a phase plate, may include a region having a flatness Rt of more than 2 μm due to wave generation on the surface or the like. In addition, the plastic substrate may also have an area having a flatness Rt of more than 2 μm. Moreover, even when the flatness Rt of the surface on which the optical film is to be bonded (the surfaces of the polarizing plate and the retardation plate) is less than 2 μm, the adhesive layer formed for the adhesion of the optical film may cause defects or deformations due to external forces exceeding 2 μm. For this reason, the method of manufacturing the laminated film of the present invention is particularly effective when the optical film is bonded to the surface where the flatness Rt may include a region exceeding 2 μm.

Hereinafter, referring to FIGS. 5A to 5D, 6A to 6D, 7A and 7B, and also to FIGS. 8A and 8B, a method of manufacturing a laminated film and a method of manufacturing a display device according to the present invention will be described.

5A shows a cross section of the adhesive film 50 in a state before it is combined with the optical film. The adhesive film 50 includes a transparent support 53 for supporting the optical film in a flat state, and adhesive layers 52 and 54 formed on both surfaces of the transparent support 53. Transparent separators (surface protective films) 51a and 51b are formed on the outer surface of the adhesive layers 52 and 54 to protect the layers. Among the adhesive layers 52 and 54, at least the adhesive layer 52 to which the optical film is to be bonded is formed of a material whose curing state is changed by application of external energy, such as a photocuring resin. Note that the adhesive layers 52, 54 and the transparent support 53 of FIG. 5A correspond to the adhesive layers 16a, 16c and the transparent support 16b of FIG. 1.

In this embodiment, a PET film having a thickness of 0.075 mm was used as the transparent support 53. The thickness of the transparent support 53 is preferably in the range of about 25 μm to 200 μm for ease of handling. As the adhesive layer 52, a photocurable resin was used. As the photocurable resin of the adhesive layer 52, it is preferable that a postcurable UV (ultraviolet) resin is used. The post-curable UV resin is, for example, Japanese Laid-Open Patent No. 9-279103 (Sekisui Chemical), the contents of which are incorporated herein by reference. The curing reaction (eg, cationic polymerization) of the post-curable UV resin is initiated by irradiating with ultraviolet rays, and the reaction proceeds slowly at room temperature. Therefore, when the curing reaction proceeds, the object (for example, the lens sheet) can be attached to the adhesive layer 52 without being fixed before the resin has completely elapsed. As the adhesive layer 54, an acrylic resin was used. As the transparent separators 51a and 51b, a PET film having a thickness of 0.05 mm was used.

The transparent separators 51a and 51b are formed to prevent defects from occurring due to the presence of foreign substances generated in the process of joining the lens sheets and the process of joining the polarizing plates, which will be described later, and these are peeled off immediately before the bonding process. The thicknesses of the separators 51a and 51b are not limited to those described above, but are determined to minimize the number of defects due to the flaws.

Table 2 below shows the thickness of the separator and the defect density with a diameter of 0.1 mm or more.

Separator Thickness (mm) Density of Defects (pcs./m ² ) Number of defects (pcs.) Appearance evaluation 0.02 200 25 X impossibility 0.03 125 15 X impossibility 0.035 50 6 △ 0.045 20 3 0 good 0.05 10 One ◎ excellent 0.20 2 0 ◎ excellent

As shown in Table 2, the density of defects due to the flaws changes by varying the thickness of the separator, and the number of defects varies with the screen size. In the case of a liquid crystal display element having a screen size of 20 inches diagonally, the number of defects becomes 25 when the thickness of the separator is 0.020 mm. With such a large number of defects, display quality is degraded. When the thickness of the separator is increased to 0.035 mm or more, the number of defects can be reduced to 10 or less, which falls within a range in which the influence is not recognized in appearance.

The adhesive film 50 having the above structure is bonded to the lens sheet in the following manner.

First, the separator 51a covering the adhesive layer 52 formed of the photocurable resin is peeled off (FIG. 5B), and the adhesive layer 52 is irradiated with light 5a (FIG. 5C). The reason why the adhesive layer 52 is irradiated with light after the separator is peeled off is to improve the light sensitivity of the adhesive layer. Alternatively, ultraviolet light can be irradiated before the separator is peeled off. In this case, however, irradiation should be carried out taking into account the ultraviolet light absorption rate (about 20%) of the separator. In this embodiment, a metal halogen lamp was used to irradiate the adhesive layer with ultraviolet light 5a. The dose was 1.6 J / cm ² .

Next, the lens sheet 55 is pressed against the adhesive layer 52. In this step, the object of the adhesive layer 52 is in the B stage (intermediate curing state). In this embodiment, a roll-to-roll method using rollers 5b and 5c to press the lens sheet 55 against the adhesive layer 52 as shown in FIG. 5D. This was used. The adhesive layer 52 is then cured to a hardness at which the lens sheet 55 is fixed to the transparent support 53 through the adhesive layer 52. After this curing step, the material of the adhesive layer 52 is at or near the C stage (completely cured state). In this embodiment, the adhesive layer 52 was cured by being left at room temperature for 24 hours together with the lens sheet 55 pressed onto the adhesive layer 52. In this way, a lamination comprising an adhesive film and a lens sheet is obtained (Fig. 6A).

A process of curing the adhesive layer 52 is described.

The gel fraction of the adhesive layer 52 varies depending on the metal, curing conditions, and the like. Depending on the gel fraction, the degree of deterioration in display quality due to the transmission of the wave on the polarizing plate to the lens sheet changes. Table 3 below shows the relationship between the gel fraction and the wave on the polarizer.

Gel fraction (wt%) Wave on polarizer 30 X impossibility 40 X impossibility 50 △ 60 O good 70 O good 80 ◎ excellent 90 ◎ excellent 95 ◎ excellent

From Table 3, it can be seen that when the gel fraction is 50 wt% or more, the influence of the wave on the polarizing plate surface can be suppressed, so that an acceptable display quality is obtained. In this embodiment, the adhesive layer 52 was cured until the adhesive layer 52 was left at room temperature for 24 hours until a gel fraction of 75 wt% was obtained.

Gel fraction was measured by the following method. First, a portion of the adhesive layer of weight w1 left for 24 hours after light irradiation was measured as a sample (w1 = 0.1 g in this example), and the sample was soaked in ethyl acetate (50 cc) for 12 hours. The ethyl acetate containing the sample was then filtered, dried (30 minutes at 110 ° C.) and left at room temperature for 30 minutes. The resulting gelled sample of weight w 2 was measured and w 2 / w 1 × 100% was calculated to determine the gel fraction.

Subsequently, another separator 51b is peeled off (FIG. 6B), and the laminated film 56 is provided, and the laminated film 56 is bonded to the polarizing plate 57a. In this embodiment, as shown in Fig. 6C, the adhesive layer 54 and the polarizing plate 57a are pressed against each other using the rollers 5b and 5c.

Finally, the polarizing plate 57a combined with the laminated film 56 is coupled to the liquid crystal display element (see FIG. 6D). In this embodiment, as shown in Fig. 7A, the polarizing plates 57a are pressed against the substrate 58a of the liquid crystal display element on the observer side using the rollers 5b and 5c. In this way, as shown in FIG. 7B, the polarizing plates 57a and 57b are disposed on the outer surface of the substrate pairs 58a and 58b sandwiching the liquid crystal material 59 as the display medium, and the liquid crystal display through the adhesive layer. A liquid crystal display device having a configuration in which the lens sheet 55 is disposed on the outer surface of the polarizing plate 57a located on the observer side of the device is obtained.

The process of bonding the lens sheet to the polarizing plate and the liquid crystal display element is not limited to that described above. Before the lens sheet 55 is bonded to the polarizing plate 57a, the lens sheet 55 is pressed against the adhesive film 50, and the adhesive layer 52 is sufficiently cured in the adhesive film 50 so that the lens sheet 55 and Other processes can be adopted as long as the lens sheet can be fixed to the adhesive film 50 by not allowing a change in the adhesion state between the adhesive layers 52. By fixing the lens sheet 55 as described above, the uneven surface of the polarizing plate 57a, in particular the wave on the surface, changes the in-plane distribution of the optical properties of the optical film so that the lens sheet 55 is bonded in a subsequent process. It is possible to reduce adversely affecting the display quality when bonded to the polarizing plate 57a through the film 50. Therefore, the bonding process is processed, for example, as shown in Figs. 8A and 8B, so that the polarizing plate 57a is previously bonded to the substrate 58a of the liquid crystal display element on the observer's side, and then the lens sheet 55 And a laminated film 56 including an adhesive film or the like is compressed with respect to the polarizing plate 57a.

The adhesive layer 54 may be formed on the surface of the polarizing plate 57a instead of the transparent support 53 of the adhesive film 50. Even in this case, after the lens sheet 55 and the adhesive film 50 are bonded to each other and the adhesive layer 52 is sufficiently cured so that the lens sheet 55 can be fixed to the adhesive layer 52 in a desired adhesive state, The resulting stack of lens sheet 55 and adhesive film 50 is bonded to polarizer 57a. By this process, it is also possible to reduce the adverse effects on the surface of the uneven surface of the polarizing plate 57a, especially the surface thereof, on the surface of the lens sheet 55.

As described above, by pressing the lens sheet 55 against the adhesive layer 52 of the adhesive film 50 and sufficiently curing the adhesive layer 52, the uneven shape of the lens array formed on the lens sheet 55 becomes a transparent support. Since it can be fixed to 53, the lens surface is prevented from being deformed by an external force. In addition, by fully curing the adhesive layer 52, the adhesive state of the lens sheet 55 is securely fixed by the transparent support 53. With this fixing, when the polarizing plate 57a is coupled to the transparent support 53 surface of the adhesive film 50 on the side opposite the lens sheet 55, the lens surface is affected by the wave on the polarizing plate 57a. Reception is prevented, and the display quality can be improved.

In FIG. 5D, the moving directions (coupling directions) of the rollers 5b and 5c are perpendicular to the extension direction of the lenticulars. The roller moving direction is not limited thereto, and may be parallel to the extension direction of the lenticular. An example of such a case is shown in FIGS. 9 and 10. FIG. 9 shows a cross-sectional view of the lens sheet 55, the adhesive layer 52, and the transparent support 53, and FIG. 10 shows a plan view of the adhesive layer 52, all of which have a lens sheet (for the adhesive layer 52). 55) shows the roller moving direction in the pressing step. As shown in FIGS. 9 and 10, pressure is applied to the lens sheet 55 with the roller 5b in a direction parallel to the extension direction of the lenticulars. By this step, a uniform pressure is applied from the center of the convex portion of each lenticular to the outside (in a direction perpendicular to the direction of extension of the lenticular). As a result, as shown in FIG. 11, the lens adhesion regions of the lens sheet 55 to the adhesive layer 52 may each be regions symmetrical with respect to the center of the convex portion of the lens, so that the visual characteristics are symmetric Can be enlarged. In the steps shown in FIGS. 7A and 8A, the contact state between the lens sheet 55 and the adhesive layer 52 is already fixed, so that the shape of the lens convex portion does not change no matter in which direction the pressure is applied to the roller. It should be noted.

In the present embodiment manufactured as described above, the luminance characteristics and visual characteristics of the liquid crystal display device were compared with the conventional liquid crystal display device having no lens sheet. The results are shown in FIGS. 12 and 13.

12 illustrates luminance characteristics of the liquid crystal display device in a vertical direction with respect to the screen (a direction in which a plurality of lenticulars are arranged, that is, a direction perpendicular to the extension direction of the lenticulars). FIG. 13 shows the visual characteristics (the relationship between the angle at which the screen is observed and the contrast) of the liquid crystal display device in the direction perpendicular to the screen. In Fig. 12 and Fig. 13, the thick line shows the characteristic of the liquid crystal display of the present embodiment, and the thin line shows the characteristic of the conventional TN liquid crystal display having no lens sheet. Both the luminance characteristic and the visual characteristic were obtained by applying a voltage signal to the liquid crystal display to achieve monochrome display and measuring the luminance at a position perpendicular to the screen using the visual measurement apparatus. Note that the measurement of the luminance characteristic shown in FIG. 12 was obtained by standardizing the luminance observed along the front direction of each liquid crystal display device.

As shown in Fig. 12, in the liquid crystal display device of the present embodiment, the change ratio of the luminance with respect to the time is small and the change of the luminance with respect to the time is also small compared with the conventional liquid crystal display. As shown in Fig. 13, the front contrast is somewhat smaller in the liquid crystal display of this embodiment than in the conventional liquid crystal display. However, since the value of the contrast ratio with respect to time is higher than the conventional value, inversion display of the image is prevented. Therefore, the liquid crystal display device can provide a wide range of visual characteristics.

Thus, in this embodiment, light is irradiated to the photocurable adhesive layer formed on the transparent support, and then the lens sheet is pressed against the adhesive layer. The adhesive layer is left in this state until the adhesive layer is cured to a strength at which the adhesive state between the lens sheet and the adhesive layer is fixed. Thereafter, the lens sheet fixed to the transparent support through the sufficiently cured adhesive layer is bonded to the polarizer through the adhesive layer. This suppresses that the uneven surface of the polarizing plate, in particular the wave on the surface, adversely affects the surface state of the optical film. In addition, the optical films can be fixed and joined without being peeled off.

A separator having a predetermined thickness is provided on the adhesive layer to which the optical film or the polarizing plate is bonded. The separator is peeled off just before bonding the optical film or the polarizing plate to the adhesive layer. This reduces the occurrence of deformation and flaws due to external force, so that a liquid crystal display device having reduced display defects can be provided.

In this embodiment, a lenticular sheet was used as the lens sheet. The lens shape is not limited to this, and may preferably be changed based on the direction in which the vision is desired to be widened. For example, a sheet with multiple hemispherical microlenses can be used when the vision is to be widened in all directions. When the vision is desired to be widened in the left and right directions, a sheet having a lens array arranged side by side with the vertical direction of the screen may be used.

The material of the transparent support is not limited to PET, and transparent resin materials such as polycarbonate (PC), polymethyl methacrylate (PMMA), and triacetyl cellulose (TAC) may be used.

(Example 2)

Embodiment 2 of the present invention will be described with reference to Figs.

14 is a cross-sectional view illustrating the liquid crystal display device used in the second embodiment of the present invention. Referring to FIG. 14, the illustrated liquid crystal display device is a reflective type, which includes a reflective liquid crystal display element 140 and a stacked layer 147. The laminated film 147 includes a transparent body 145 and a prism sheet 146 which is an optical film, and the transparent body 145 includes a first adhesive layer 145a, a transparent support 145b, and a second adhesive layer ( 145c).

The reflective liquid crystal display device 140 basically comprises: a thin film transistor (TFT) arranged in a matrix on a substrate formed of glass, plastic, monocrystalline silicon, or the like, and an active matrix substrate including a transparent pixel electrode and a reflector 142. (141a); TN liquid crystal material 143 with a twist angle of 45 degrees; And a counter substrate 141b having a transparent electrode and a color filter formed thereon. The substrates 141a and 141b are sealed with a liquid crystal material 143 therebetween and bonded with a sealant. The λ / 4 plate 144b and the polarizing plate 144a are disposed on the outer surface of the counter substrate 141a of the reflective liquid crystal display element 140, that is, on the observer side.

Referring to Fig. 15, the display principle of the reflective liquid crystal display element of this embodiment is explained.

The incident irradiation light 155 passes through the polarizing plate 154a and the λ / 4 plate 154b and is reflected by the reflector 152. During this passage, the polarization state of the irradiation light 155 is modulated in the liquid crystal layer 153, where the amount of light emitted from the reflective liquid crystal display element is controlled to display an image.

More specifically, the polarizing plate 154a is arranged such that its transmission axis or absorption axis is at an angle of 45 ° with respect to the phase retardation axis (low speed axis) or phase advance axis (high speed axis) of the λ / 4 plate 154b. The linearly polarized light passing through the polarizing plate 154a of the illumination light 155 is changed into circularly polarized light by the λ / 4 plate 154b before being incident on the reflective liquid crystal display element. When the liquid crystal layer 153 of the liquid crystal display element does not modulate the circularly polarized incident light, the rotation direction of the circularly polarized light is reversed when reflected by the reflector 152. The reflected circularly polarized light is returned to the polarizing plate 154a through the λ / 4 plate 154b, where the circularly polarized light is changed and absorbed into linearly polarized light that is orthogonal to the transmission axis of the polarizing plate 154a. As a result, black is displayed.

When the liquid crystal layer 153 of the liquid crystal display element modulates the circularly polarized incident light so that the circularly polarized light is not changed, the reflected circularly polarized light is returned to the polarizing plate 154a through the λ / 4 plate 154b. The circularly polarized light is matched with the transmission axis of the polarizing plate 154a to be converted into linearly polarized light and output. As a result, the color is displayed.

The direction of the transmission axis of the polarizing plate 154a and the phase retardation axis of the λ / 4 plate 154b are determined in consideration of the kind of liquid crystal material, the direction of orientation, visual characteristics, and the like. As the retardation plate, a laminated structure of λ / 2 plate and λ / 4 plate may be used.

In the present embodiment, for the color display, three main color red (R), green (G), and blue (B) color filters are arranged on the counter substrate 141b for each pixel as described above. The color is colored to the light passing through each color filter. The R, G, and B pixels can be arranged in various array patterns, such as the stripe array shown in FIG. 2A and the delta array shown in FIG. 2B, wherein the image elements are arranged repeatedly in the horizontal and vertical directions.

The size and number of pixels of each pixel change depending on the panel size. In this embodiment, a 3.9-inch reflective type with 320 (R, G, and B, respectively) horizontal pixels x 240 vertical pixels, a horizontal pixel pitch Ph of 0.0826 mm, and a vertical pixel pitch Pv of 0.248 mm in a stripe array. Liquid crystal display elements were used.

The color filter does not necessarily have to be provided on the counter substrate. For example, it can be formed on the pixel electrode of the active matrix substrate.

A prism sheet 146 coupled to the outer surface of the polarizing plate 144a on the viewer side through the transparent body 145 is described with reference to FIG. 16. Note that the prism sheet indicated by reference numeral 166 in FIG. 16 is the same as the prism sheet shown in FIG. 14.

Prism sheet 166 includes a plurality of prisms 166a arranged parallel to each other. In this embodiment, a plurality of prisms are arranged to extend in a direction parallel to the lateral direction of the screen of the liquid crystal display element to widen the view in the vertical direction with respect to the screen.

Prism sheet 166 is formed using a repeating prism shaped mold, for example, by transferring the repeating prism shape to the acrylic material by injection molding. In this embodiment, a prism 166a having a pitch P2 of 0.10 mm, a height h2 of 0.027 mm, an angle θ1 of 15 ° ± 2 °, and an angle θ2 of 90 ° ± 2 °.

An anti-reflection film (not shown) may be formed on the surface of the prism sheet 166 opposite to the surface on which the prism is formed. This improves the transmittance of the prism sheet 166. In this embodiment, an antireflection film including MgF ₂ thin films and SiO ₂ thin films alternately stacked with a thickness of about 0.1 μm was directly formed by a vapor deposition method. The reflected energy can be reduced by the interference between the thin films. With this antireflective film, surface reflection of about 4% is successfully reduced to reflection of 1% or less, thereby improving the transmittance of the prism sheet 166.

Next, the transparent body used in the present embodiment will be described in detail, and then the method for manufacturing the liquid crystal display device in this embodiment will be briefly described.

The transparent body 145 of FIG. 14 including the transparent support 145b and the adhesive layers 145a and 145c formed on both surfaces of the transparent support 145b is made using the adhesive film 170 shown in FIG. 17A. Note that the transparent support 145b and adhesive layers 145a and 145b in FIG. 14 correspond to the transparent support 173 and adhesive layers 172 and 174 shown in FIG. 17A, respectively. As shown in FIG. 17A, the adhesive layers 172, 174 are formed on opposing surfaces of the transparent support 173 and are protected by separators 171a, 172b formed thereon.

At least one of the two adhesive layers to which the optical film (the prism sheet in this embodiment) is bonded is formed of a material such that photocurable resin is applied, and the curing state is changed by applying external energy. In this embodiment, the adhesive layer 172 is formed of a photocurable resin, and the adhesive layer 174 is formed of an acrylic resin. As the transparent support 173, a PET film having a thickness of 0.075 mm was used. As the separators 171a and 171b, a PET film having a thickness of 0.05 mm was used. The thickness of the separator is not limited to this, and is determined to minimize the number of defects due to the defect, for example, as in the thickness of the separator used in Example 1.

First, as in Example 1, the prism sheet, which is an optical sheet, is bonded to the adhesive film 170. Specifically, as shown in FIG. 17B, the separator 171a covering the adhesive layer 172 of the adhesive film 170 is peeled off, and light 17a is irradiated onto the adhesive layer 172 as shown in FIG. 17C. Then, as shown in FIG. 17D, the prism sheet 176 is pressed against the adhesive layer 172. In this embodiment, 1.6 J / cm ² ultraviolet light was irradiated to the adhesive layer 172 using a metal halogen lamp, and the prism sheet 176 was pressed against the adhesive layer 172 by rollers 17b and 17c.

With the prism sheet 176 pressed against the adhesive layer 172, the adhesive layer 172 is cured to such an extent that the adhesive state between the prism sheet 176 and the adhesive layer 172 remains unchanged in a subsequent process (Fig. 18a). Specifically, as described in Example 1, the adhesive layer 172 is preferably cured until a gel fraction of at least 50 wt% is obtained. In this embodiment, as in Example 1, the adhesive layer 172 was left at room temperature for 24 hours to obtain a gel fraction of about 75 wt%.

By curing the adhesive layer 172 as described above, the transparent support 173 can support the prism sheet 176 in a substantially flat state. As a result, in the subsequent process, when the prism sheet 176 is coupled with the rough surface having a somewhat irregular shape such as the polarizer surface through the transparent support 173, the rough surface unevenness of the prism sheet 176 Delivery can be reduced.

After curing the adhesive layer 172, the separator 171b is peeled off (FIG. 18B), and the polarizing plate 175 is pressed against the adhesive layer 174 by rollers 17b and 17c (FIG. 18C), and the prism sheet ( 176 and the polarizing plate 175 produce a laminate bonded through an adhesive film (FIG. 18D). The resulting stack is bonded to the substrate of the reflective liquid crystal display element on the observer's side (FIG. 19A) to obtain the reflective liquid crystal display device of this embodiment (FIG. 19B).

The process of bonding the prism sheet 176 to the polarizing plate 175 and the reflective liquid crystal display element is not limited to the above. The prism sheet is bonded to the polarizing plate by pressing the prism sheet against the adhesive film and sufficiently curing the adhesive layer existing between the prism sheet and the adhesive film so that a change in the adhesion state between the prism sheet and the contact layer is not allowed in a subsequent process. Any other method may be adopted as long as the prism sheet can be fixed to the adhesive film before becoming. By fixing the prism as described above, it is possible to reduce that the uneven surface of the polarizing plate, in particular the wave on the surface, is transmitted to the prism sheet to adversely affect the display quality. Therefore, as shown, for example, in FIGS. 20A and 20B, the polarizing plate 175 is previously bonded to the substrate 177a of the liquid crystal display element on the observer's side, and then the lamination of the prism sheet 176 and the adhesive film is carried out. A bonding process that is pressed against 175 may proceed.

The adhesive layer 174 may be formed on the surface of the polarizer 175 instead of on the transparent support 173. Even in this case, after the prism sheet 176 and the adhesive film 170 are bonded and the adhesive layer 172 is sufficiently cured so that the prism sheet 176 can be fixed to the adhesive film 170 in a desired fixing state, The resulting stack of prism sheet 176 and adhesive film 170 is bonded to polarizer 175. With this process, it is also possible to reduce the impact of the uneven surface of the polarizing plate 175, in particular the wave on the surface, on the surface of the prism sheet 176.

As described above, the unevenness of the prism array formed on the prism sheet 176 by pressing the prism sheet 176 against the adhesive layer 172 of the adhesive film 170 and then curing the adhesive layer 172 sufficiently. The shape may be fixed to the transparent support 173. Therefore, the prism surface is prevented from being deformed by an external force. In addition, by fully curing the adhesive layer 172, the adhesive state of the prism sheet 176 is securely fixed by the transparent support 173. This fixing prevents the prism surface from being affected by waves on the polarizer 175 when the polarizer 175 is bonded to the surface of the transparent support 173 of the adhesive film on the side opposite the prism sheet 176. Thus, the display quality is improved.

In the reflective liquid crystal display device of the present embodiment manufactured in the manner described above, as shown in FIG. 21, illumination light incident on the display screen at an angle of about 30 ° from the normal direction of the display screen is output in the normal direction of the display screen. Reflected by the reflector as much as possible. This allows the specularly reflected image from the reflector to be observed as the display image, so that bright display is possible. In addition, the specularly reflected light from the prism sheet surface is reflected in a direction different from the direction in which the display image is reflected. Thus, specular reflection does not adversely affect the display.

As described above, in the liquid crystal display device of this embodiment, a laminated film including a prism sheet having a plurality of uneven portions and an adhesive film is bonded to a polarizing plate arranged on the observer side of the liquid crystal display element. In particular, the prism sheet is pressed against the photocurable adhesive layer and fixed, and the optical film is bonded to the polarizing plate through the transparent support. With this structure, waves generated on the surface of the polarizing plate can be absorbed and reduced. In addition, the adhesive sheets can be fixed and joined without being peeled off. In the resulting liquid crystal display device, there is no deterioration in display quality.

A separator having a predetermined thickness is disposed on the outer surface of the adhesive film to prevent the occurrence of deformation and flaws due to external force while bonding the prism sheet to the adhesive layer. In this way, a liquid crystal display device having reduced display defects is provided.

The prism sheet is pressed against the curable adhesive layer and fixed, and then the adhesive film is pressed against the polarizing plate. In this way, the optical film and the polarizing film can be bonded to each other and fixed. Thus, a manufacturing method capable of preventing the influence of the wave on the surface of the polarizing plate can be provided.

It is to be noted that the shape of the prism sheet used in this embodiment is not limited to that described above, and may be appropriately selected depending on the refractive index of the prism sheet and the desired illumination environment (direction of illumination light).

As described above, in the method of manufacturing a laminate film according to the present invention, after external energy is applied to an adhesive layer formed of a material whose curing state is changed by the application of external energy, the optical film is pressed against the adhesive layer. . Subsequently, the adhesive layer is cured to a hardness at which the adhesive state between the optical film and the adhesive layer is fixed. By the above method, a laminated film including an optical film in which the optical film is kept in a substantially flat state by the transparent support through the adhesive layer can be obtained. When the laminated film is bonded to a polarizing plate or the like on which a wave is generated on the surface, it is possible to prevent the occurrence of in-plane change in the surface state of the optical film due to the wave or the like, thereby obtaining uniform optical characteristics for the optical film. Therefore, by combining the laminated film with the display element, it is possible to overcome the problem that the display quality is degraded due to the distortion of the lens characteristics.

In particular, by using a photocuring resin which is a material whose curing state changes with the application of external energy, the optical film and the transparent support can be easily combined and fixed together. Therefore, occurrence of defects due to external forces and flaws can be reduced.

By using a lens sheet having a plurality of microlens arrays as the optical film, it is possible to reduce the distortion of the lens characteristics of the lens sheet sensitive to the contact state with the adhesive layer, and the wave and external force on the polarizing plate. There is provided a high performance laminated film which can suppress the display quality from deteriorating due to the deformation and the occurrence of scratches.

By disposing a surface protective film having a thickness t in the range of 0.035 mm ≤ t ≤ 0.2 mm on the outer surface of the adhesive layer formed on the adhesive film, it is possible to prevent the adhesive layer from being deformed due to the presence of foreign matter and external force before curing, The number of defects that may degrade the display quality is reduced. As a result, the coupling between the optical film and the transparent body becomes easy.

In the method of manufacturing the display device according to the present invention, a laminated film including the optical film described above is disposed on the observer side of the display element. With this structure, it is possible to prevent the surface of the uneven surface of the display element to which the laminated film is bonded, in particular the wave on the surface thereof, from being transferred to the optical film to cause a change in the optical properties. As a result, it is possible to provide a display device in which optical characteristics including visual characteristics in particular are improved without degrading display quality.

While the invention has been described in the preferred embodiments, it will be apparent to those skilled in the art that the described invention may be modified in various ways, and that other embodiments than those described and specifically described above may be assumed. Accordingly, the appended claims are intended to cover all modifications of the invention that fall within the true intent and scope of the invention.

Claims (30)

Transparent support and optical film having two opposing surfaces-The optical film is applied to one of two opposing surfaces of the transparent support via a first adhesive layer made of a material whose curing state is changed by the application of external energy. In the method of manufacturing a laminate film having-formed, Applying external energy to the first adhesive layer; Bonding the optical layer to the adhesive layer by compressing the optical layer on the adhesive layer; And Curing the adhesive layer to a hardness at which the optical film and the adhesive layer maintain bonding and the adhesion state between the adhesive layer and the optical film is fixed. Laminated film manufacturing method comprising a. The method of claim 1, The adhesive layer is a laminated film manufacturing method, characterized in that formed of an ultraviolet-curable resin (ultraviolet-curable resin). The method of claim 1, Curing the adhesive layer comprises the step of leaving the adhesive layer and the optical film in a state in which the adhesive layer and the optical film to maintain the bonding. The method of claim 1, The curing of the adhesive layer may include leaving the adhesive layer and the optical film in a state in which the adhesive layer and the optical film maintain the bonding so that the gel fraction of the adhesive layer is 50 wt% or more. Laminated film production method. The method of claim 1, On the adhesive layer is provided a surface protective film for protecting the adhesive layer, the thickness t of the surface protective film is in the range of 0.035mm ≤ t ≤ 0.2mm, And the method further comprises peeling the surface protective film prior to the step of pressing the optical film against the adhesive layer. The method of claim 1, And a rough surface is bonded to the other surface of the opposing surface of the transparent support through the second adhesive layer. The method of claim 6, And said rough surface is the surface of the film made by drawing. The method of claim 6, The rough surface is defined as the roughness Rt1 as the distance between the highest point and the deepest point in the range of lengths to be evaluated. Rt1> 2 μm And a region having flatness Rt1 that satisfies the requirements. The method of claim 1, The transparent support is defined as the flatness Rt2 as the distance between the highest point and the deepest point in the range of the evaluated length, Rt2 ≤ 2μm It has a flatness Rt2 which satisfy | fills the laminated film manufacturing method characterized by the above-mentioned. The method of claim 1, The optical film is a lens sheet having a plurality of lenses formed on at least one surface, the surface having the plurality of lenses is pressed against the adhesive layer facing the first adhesive layer. . The method of claim 10, The lens sheet is a lenticular sheet having a plurality of semi-cylindrical lenticules extending in parallel to each other, Wherein the lenticular sheet is pressed against the first adhesive layer by a force applied in an extension direction of the lenticular with the surfaces having the plurality of lenticulars facing the first adhesive layer. . The method of claim 1, The optical film is a laminated film manufacturing method, characterized in that the prism sheet having a plurality of prism. A transparent support having two opposing surfaces; An adhesive layer formed on one of two opposing surfaces of the transparent support; And An optical film coupled to the transparent support through the adhesive layer Including, The adhesive layer is formed of a material whose curing state is changed by the application of external energy, The transparent support is defined as the flatness Rt as the distance between the highest point and the deepest point in the range of the evaluated length. Rt ≤ 2μm It has a flatness Rt which satisfy | fills the laminated film characterized by the above-mentioned. The method of claim 13, Laminated membrane, characterized in that the adhesive layer has a gel fraction of 50wt% or more. The method of claim 13, And the optical film is a lens sheet having a plurality of lenses formed on at least one surface, and the surface having the plurality of lenses is pressed against the adhesive layer to face the adhesive layer. The method of claim 13, The optical film is a laminated film, characterized in that the prism sheet having a plurality of prisms. In the manufacturing method of the display apparatus provided with a display element and the optical film arrange | positioned at the observer side of the said display element, Manufacturing the display element; And Bonding the optical film to a surface of the display element on the observer side through an adhesive film; Including but not limited to: The adhesive film comprises a transparent support having a first adhesive layer formed on one of the two opposite surfaces, the first adhesive layer is made of a material whose curing state is changed by the application of external energy, The step of bonding the optical film to the surface of the display element on the observer's side is: Applying external energy to the first adhesive layer; Bonding the optical film to the first adhesive layer by pressing the optical film on the first adhesive layer; Curing the first adhesive layer to a hardness at which the optical film and the first adhesive layer maintain bonding and the adhesion state between the optical film and the first adhesive layer is fixed; And After curing of the first adhesive layer, bonding the display element with another one of two opposite surfaces of the transparent supporter through a second adhesive layer; Display device manufacturing method comprising a. The method of claim 17, The display element includes a pair of substrates, a liquid crystal material sandwiched between the pair of substrates, and an optical property changing means disposed at least on the observer side of the pair of substrates to change the optical properties of the incident light. It is a display element And said optical film is bonded to said liquid crystal display element by bonding said optical property changing means and said transparent support of said adhesive film through said second adhesive layer. The method of claim 17, The first adhesive layer is formed of an ultraviolet-curing resin. The method of claim 17, And curing the first adhesive layer comprises leaving the first adhesive layer and the optical film in a state in which the first adhesive layer and the optical film are bonded to each other. The method of claim 17, Curing the first adhesive layer may include leaving the first adhesive layer and the optical film in a state in which the first adhesive layer and the optical film maintain bonding so that the gel fraction of the first adhesive layer is 50 wt% or more. Display device manufacturing method characterized by the above-mentioned. The method of claim 17, On at least the first adhesive layer is provided with a surface protective film for protecting the first adhesive layer, the thickness t of the surface protective film is in the range of 0.035mm ≤ t ≤ 0.2mm, And the method further comprises peeling the surface protective film prior to the step of pressing the optical film against the first adhesive layer. The method of claim 17, When the surface of the display element bonded to the second adhesive layer defines the flatness Rt1 as the distance between the highest point and the deepest point within the range of the evaluated length Rt1> 2 μm And a region having flatness Rt1 that satisfies the requirement. The method of claim 17, The transparent support is defined as the flatness Rt2 as the distance between the highest point and the deepest point in the range of the evaluated length, Rt2 ≤ 2μm A display device manufacturing method characterized by having a flatness Rt2 which satisfies. The method of claim 18, And said optical property changing means is a polarizing plate. The method of claim 18, And the means for changing the optical characteristics is a phase plate. The method of claim 17, And the optical film is a lens sheet having a plurality of lenses, and a surface having the plurality of lenses is pressed against the first adhesive layer to face the first adhesive layer. The method of claim 27, The lens sheet is a lenticular sheet having a plurality of semi-cylindrical lenticulars extending parallel to each other, And the lenticular sheet is pressed against the first adhesive layer by a force applied in an extension direction of the lenticular with the surfaces having the plurality of lenticulars facing the first adhesive layer. . The method of claim 17, And the optical film is a prism sheet having a plurality of prisms. A display device and a lens sheet disposed on an observer side of the display device, wherein the lens sheet has a plurality of lenticulars extending in parallel to each other. Manufacturing the display element; Forming an adhesive layer on an observer side of the display element; Disposing the lens sheet such that the lens surface of the lenticular faces the adhesive layer; And Pressing the lens sheet against the adhesive layer by applying a force in an extension direction of the lenticulars Display device manufacturing method comprising a.